With regard at a general level to heating methods that use steam for heating, for example, the use of saturated steam or so-called steam heating (steaming) and high-pressure steam heating using high-pressure steam generated from a boiler are known; also known is superheated steam heating, which uses high-temperature, high-pressure superheated water vapor (superheated steam) that is produced when high-pressure steam generated from a boiler is additionally heated to high temperatures. Among these, steam heating is a method in which the material to be treated is subjected to heat treatment by so-called “steaming”, in which a heating chamber is filled with steam produced by heating water to about 100 to 120° C. High-pressure steam heating using high-pressure steam from a boiler is a method in which the material to be treated is subjected to heat treatment using as the heat source saturated steam that has been pressurized and brought to a higher temperature.
Superheated steam heating, on the other hand, is a method in which high-pressure steam produced from a boiler is additionally heated to a higher temperature of at least 140° C., yielding a thermal energetically quasi-stable superheated steam, which is injected into a heating chamber to fill same and thereby subject the material to be treated to heat treatment. Since a dry high-temperature, high-pressure atmosphere is formed by the superheated steam in this method, this heating method is used as a heating means that approximates baking. Since superheated steam heating can employ a high-temperature, high-pressure, high-caloric, and thermal energetically quasi-stable dry steam, a broad range of applied technology has been proposed for superheated steam heating in the form of, for example, means for heating and baking food products, means for roasting wastes from the agricultural and livestock industries, means for the carbonization of, for example, wood, and means for cleaning, for example, metal surfaces (Japanese Patent Application Laid-open Numbers Hei 06-090677, 2001-061655, 2001-214177, 2001-323085, and 2002-194362).
However, this type of heating method suffers from a number of problems, for example, a boiler is required to generate high-pressure, high-temperature steam and a high-temperature heating means is required to subject the high-temperature, high-pressure steam from the boiler to additional heating; the facility scale is large; a large energy loss is incurred in order to inject the high-temperature, high-pressure superheated steam into the heating chamber, yielding a lower efficiency than in established baking methods; so-called ordinary steam heating is satisfactory in many cases, so there is presumably little requirement for the utilization of superheated steam heating; this type of method is unsuitable for small runs; and, since the baking effect has yet to be thoroughly identified, there is some distance to go in order to realize practical application. Moreover, these problems have yet to be solved.